Exemplary embodiments of the present disclosure relate to a deaerator, and more particularly, to a deaerator for a thermal power plant capable of increasing a deaeration effect by making a direction of steam sprayed from a steam supply unit in an internal space of a tank the same of different as a direction of water sprayed from a spray unit.
Generally, a thermal power plant is an apparatus that converts heat energy generated by combusting fossil fuel such as coal, petroleum, and gas into mechanical energy and then produces electric energy using a steam turbine.
The steam turbine generates shaft power while being supplied with high temperature high pressure superheated steam to drop a pressure to a low pressure to operate a power generator, thereby producing electricity. Air is introduced in a last step during the process. The introduced air is removed by a vacuum pump or an ejector in a steam condenser. However, when condensed water is sub-cooled, some of the air is dissolved in water.
FIG. 1 is a configuration diagram of a thermal power generation system.
As illustrated in FIG. 1, water is discharged as high temperature high pressure steam from a boiler 1 during the power generation of the thermal power plant.
The discharged high temperature high pressure steam is introduced into a steam turbine 2 to be discharged as low temperature low pressure vapor while heat energy of steam is converted into mechanical energy. In this case, the shaft of the turbine is rotated to produce electricity.
A process of converting low temperature low pressure vapor into water in a condenser 3 is repeated.
Since impurities such as inorganic matters are accumulated in the boiler, about 4-5% of the water is discharged and new water is injected. Since the new water includes oxygen, when there is a need to inject a lot of water during the power generation, a condenser tank 4 is installed at a rear end of the condenser.
In this case, a deaerator 5 is used to remove oxygen dissolved in the injected water. When water passes through a feed water heater while it moves to the deaerator 5, temperature rises and the oxygen dissolved in the water chemically reacts to organic matter dissolved in the water in an activated gas state to be converted into impurities. Some of the so produced impurities stick on a surface of a heat exchanger. Further, the impurities that are stuck on a surface of the boiler accelerate oxidation corrosion of iron.
To address the above problem, the deaerator is used prior to delivering the supplemental water to a condensation water tank to remove oxygen dissolved in the supplemental water and then deliver water to the condensation water tank. That is, generally, the deaerator is an apparatus for removing gas, in particular oxygen, dissolved in water.
Generally, the existing thermal power plant has used a spray tray type of deaerator. However, the existing deaerator may have a small residence time of steam and may not increase a contact surface area of water with steam as the steam supplied from the steam supply unit is sprayed only in one direction, and therefore to increase the deaeration, a capacity or a size of the deaerator needs to be increased, such that the deaerator may hardly be miniaturized.
Further, the existing deaerator has a problem in that a tube of the heat exchanger of the boiler may be corroded because the deaeration effect is not increased and thus gases such as oxygen are included in water supplied to the boiler.
In addition, the existing deaerator has a problem in that performance of the heat exchanger, that is, efficiency of the thermal power plant is reduced.